Manipulator

ABSTRACT

A manipulator for producing a remote center of revolute motion is provided. The manipulator includes a base and a first parallelogram linkage mechanism including a first link pivotally mounted to the base for rotation about a first axis such that the first link moves in a first plane. The manipulator also includes a second parallelogram linkage mechanism including a second link pivotally mounted to the base for rotation about a second axis such that the second link moves in a second plane parallel to the first plane. The first link is pivotal about a third axis perpendicular to the first axis and the second link is pivotal about a fourth axis perpendicular to the second axis. The first and second parallelogram linkages are pivotally connected together by a first connector link and a second connector link. The first and second connector links are parallel to each other and parallel to the first and second axes such that the first and second planes remain parallel as the first and second links respectively rotate about the third and fourth axes. A tool holder is pivotally connected to the first connector link by a first pivot joint and pivotally connected to the second connector link by a second pivot joint such that a tool held therein is pivotable at a remote virtual pivot point about a first remote pivot axis by pivoting the first and second links respectively about the first and second axes and a second remote pivot axis by pivoting the first and second links respectively about the third and fourth axes.

CROSS-REFERENCE TO RELATED APPLICATION

[0001] This application is a divisional application of copending U.S.patent application Ser. No. 09/710,631, filed Nov. 1, 1990 which claimsthe benefit of U.S. Provisional Application No. 60/165,046 filed Nov.12, 1999, the disclosures of which are incorporated herein by reference.

FIELD OF THE INVENTION

[0002] This invention relates to a manipulator capable of manipulating atool or other object with one or more rotational degrees of freedom in aspherical coordinate system.

BACKGROUND OF THE INVENTION

[0003] In various applications, it is desirable to be able to pivot atool or other object about a point in space which is remote fromequipment supporting the tool. Such a point in space is sometimes calleda virtual pivot point or a remote center of motion. An example of asituation in which it is useful to be able to pivot a tool about avirtual pivot point is in medical procedures. A medical tool often needsto be pivoted about a point in, on, or in proximity to a patient's body,but it may be undesirable to have support structure for the tool locatedat the point, since the support structure may introduce contaminationinto the patient's body or interfere with the view of or access to thepatient by persons performing the medical procedures. A manipulatorwhich can pivot a tool about a virtual pivot point can avoid suchdisadvantages of support structure.

[0004] One known type of manipulator capable of pivoting a tool inproximity to a virtual pivot point employs a parallel linkage tomaintain the orientation of a rod-like tool remotely from the actuationpoint. The parallel linkage is attached to a rotating base assembly orhas some other similar rotating structure at the base which allows thetool to be manipulated in two degrees of freedom (DOF) in a sphericalcoordinate system. An example of such a manipulator is described in U.S.Pat. No. 5,397,323 entitled “Remote Center-Of-Motion Robot For Surgery”.This and other conventional parallel linkage manipulators have thedrawback that the virtual pivot point must lie on a rotational axis oftwo of the links of the linkage. More specifically, the virtual pivotpoint must lie in the same plane as the rotational axis of the base andmust be inline with the distal pivots of the manipulator. Themanipulator disclosed in U.S. Pat. No. 5,397,323 only produces anapproximate remote center of motion if the tool is mounted in from thedistal pivots, since the tool actually sweeps an arc in one plane ratherthan pivoting around a point.

[0005] One disadvantage of these constraints on the location of thevirtual pivot point is that it can be difficult to position themanipulator with respect to a patient's body and other equipment. Inparticular, the requirement that the virtual pivot lie in the same planeas the rotating structure at the base can cause clearance problems witha patient or with other equipment being used in the medical proceduresuch as imaging equipment. The clearance problems can require thepatient or a person performing a medical procedure to assume anuncomfortable position.

[0006] In addition, the requirement that the virtual pivot point beinline with the distal pivots of the manipulator can make conventionalparallel linkage manipulators difficult to use in biopsies and othermedical procedures performed in conjunction with imaging systems such ascomputer tomography (CT) equipment, x-ray equipment or magneticresonance imaging equipment. In a biopsy performed using imagingequipment, a biopsy needle is inserted into a patient's body while thepatient is outside the imaging equipment. The patient is then placedinside the imaging equipment and an image is taken to determine thelocation of the biopsy needle with respect to the region of the bodywhere the biopsy is to be performed. It is frequently difficult orunsafe for a human operator to adjust the position of the biopsy needlewhile an image is being taken. For example, there often is a verylimited amount of space between the interior of the imaging equipmentand the patient's body. Additionally, the operator could be exposed toharmful radiation from the imaging equipment or the operator couldinterfere with the imaging process. Thus, each time the position of thebiopsy needle has to adjusted, the patient is withdrawn from the imagingequipment and then reintroduced into the imaging equipment after theposition of the biopsy needle has been adjusted. Obviously, such aprocedure is very time consuming and imprecise.

[0007] Recent advances in CT technology have decreased the time togenerate an image to the point that near real time video images can beproduced. With this technology, a doctor can place a medical tool withhigh precision, but he must be very close to the radiation source andreceives a higher dose of harmful radiation.

[0008] One way in which these problems can be addressed is by using amanipulator that is capable of adjusting the position of a needle orobject with respect to a patient's body while imaging is being carriedout. However, with conventional parallel linkage manipulators that canproduce a remote center of motion, the distal pivots are in the sameplane as the image of interest and tend to distort that image. If thetool is offset from the distal pivots of the manipulator, as is the casewith the manipulator described in U.S. Pat. No. 5,397,323, the tool willno longer rotate about a true virtual pivot point. Instead, the toolwill move in a small arc as the manipulator is swung about.

SUMMARY OF THE INVENTION

[0009] Accordingly, in view of the foregoing, a general object of thepresent invention is to provide a manipulator capable of manipulating atool or other object with two rotational degrees of freedom about avirtual pivot point with fewer constraints on the position of themanipulator relative to the virtual pivot point than with conventionalmanipulators.

[0010] Definition Of Terms

[0011] The term link will be used herein to refer to a member whichfunctions as the equivalent of a rigid body when moving parallel to aspecific plane. Thus, a link may be a rigid body, or it may comprise aplurality of components which can move together as a single bodyparallel to the specific plane but which are movable with respect toeach other in a plane transverse to the specific plane. For example, insome embodiments, a group of components which function as a parallellinkage for movement parallel to a first plane may function as a singlelink for movement parallel to a second plane transverse to the firstplane.

[0012] Two links are considered parallel to each other when a lineconnecting two rotational axes of one link is parallel to a lineconnecting two rotational axes of the other link.

[0013] The term pivot point will be used to refer to a point at which alink is physically connected to another member for pivoting with respectto the other member about an axis, while the term virtual pivot pointwill refer to a point in space at which a link can pivot about an axispassing through the virtual pivot point without the link having to bephysically supported at the virtual pivot point. Pivot can provide one,two or three degrees of rotational freedom.

BRIEF DESCRIPTION OF THE DRAWINGS

[0014]FIG. 1 is a schematic side elevation of a kinematic model of anexample of a conventional parallel linkage manipulator.

[0015]FIG. 2 is a schematic side elevation of a kinematic model of oneaspect of a manipulator according to the present invention.

[0016]FIGS. 3 and 4 are schematic side views of two examples of linkswhich can be employed in the present invention.

[0017]FIG. 5 is a schematic side elevation of a kinematic model of avariation of the example of FIG. 2.

[0018]FIG. 6 is a schematic side elevation of a kinematic model ofanother variation of the example of FIG. 2.

[0019]FIG. 7 is an isometric view of another embodiment of a manipulatorconstructed in accordance with the present invention.

[0020]FIG. 8a is an isometric view and FIG. 8b is a front elevation of akinematic model of another aspect of a manipulator according to thepresent invention.

[0021]FIG. 9 is an isometric view of an embodiment of a manipulatoraccording to the present invention.

[0022]FIG. 10 is a side elevation of the embodiment of FIG. 9.

[0023]FIGS. 11 and 12 are respectively a side elevation and an isometricview of the embodiment of FIG. 9 rotated backwards from the positionshown in FIG. 9.

[0024]FIGS. 13, 14, and 15 are respectively a side elevation, anisometric view, and a front elevation of the embodiment of FIG. 9rotated sideways from the position shown in FIG. 9.

[0025]FIG. 16 illustrates an example of the use of motors to drive theembodiment of FIG. 9.

[0026]FIG. 17 is an isometric view of another embodiment of amanipulator according to the present invention.

[0027]FIG. 18 is a side elevation of the embodiment of FIG. 15.

[0028]FIGS. 19 and 20 are respectively a side elevation and an isometricview of the embodiment of FIG. 18 rotated backwards from the positionshown in FIG. 18.

[0029]FIGS. 21, 22, and 23 are respectively a side elevation, anisometric view, and a front elevation of the embodiment of FIG. 18rotated sideways from the position shown in FIG. 18.

[0030]FIGS. 24 and 25 are schematic side elevations of links equippedwith different means for maintaining the attitude of links from thatshown in FIG. 18.

[0031]FIG. 26 is an isometric view of another embodiment of amanipulator according to the present invention.

[0032]FIG. 27 is a side elevation of the embodiment of FIG. 26.

[0033]FIG. 28 is a side elevation of a portion of the embodiment of FIG.26 supporting a tool holder.

[0034]FIG. 29 is a side elevation view of an embodiment of the toolholder of FIG. 28.

[0035]FIG. 30 is a top view of the tool holder of FIG. 29 with thecartridge removed.

[0036]FIG. 31 is a isometric view of the cartridge of FIG. 29 with aneedle removed.

[0037]FIG. 32 is a side elevation of the cartridge of FIG. 29 in apartially disassembled state.

[0038]FIG. 33 is an enlarged transverse cross-sectional view of thecarriage guide of the cartridge of FIG. 31.

[0039]FIG. 34 is a plan view of the carriage drive unit of the toolholder of FIG. 29 with the cover of the drive unit shown in phantom.

[0040]FIG. 35 is a side elevation of the carriage drive unit of FIG. 34.

[0041]FIGS. 36 and 37 are longitudinal cross-sectional views of thedispensing units of the cartridge of FIG. 31.

[0042] While the invention will be described and disclosed in connectionwith certain preferred embodiments and procedures, it is not intended tolimit the invention to those specific embodiments. Rather it is intendedto cover all such alternative embodiments and modifications as fallwithin the spirit and scope of the invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

[0043] Referring now more particularly to FIG. 1 of the drawings thereis schematically shown a kinematic model of a conventional parallellinkage manipulator in which the virtual pivot point or remote center ofmotion produced by the manipulator is constrained to lie in the sameplane as the roll axis of the main mechanism and to be inline with thedistal pivots. The illustrated conventional manipulator includes twoparallel linkages 10 and 20, each linkage having a plurality of linksmovable parallel to the plane of the drawing. For ease of viewing, therotational axes of the links are shown extending diagonally, but theyactually extend perpendicular to the plane of the drawing.

[0044] A first parallel linkage 10 includes three links 11, 12, and 13.Links 11 and 12 are pivotable about parallel axes 14 and 15 at theirlower ends, which may be supported by a base 18 or other supportstructure such that axes 14 and 15 remain stationary with respect toeach other. Links 11 and 12 are also pivotably connected to link 13 attheir upper ends for pivoting about axes 16 and 17, which are bothparallel to axis 14. A plane containing axes 16 and 17 is parallel to aplane containing axes 14 and 15, and a plane containing axes 14 and 16is parallel to a plane containing axes 15 and 17.

[0045] The second parallel linkage 20 includes four links, i.e., link12, link 21, link 22, and link 23 which supports a tool 24. Link 21,which is rigidly connected to link 13, is pivotably connected at itsopposite ends to links 12 and 23 for pivoting about axis 17 and axis 26,which are parallel to axis 14. Link 22, in turn, is pivotably connectedat its opposite ends to links 12 and 23 for pivoting about axis 25 andaxis 27, both of which are parallel to axis 14. Axis 26 is coplanar withaxes 16 and 17. A plane containing axes 25 and 27 is parallel to a planecontaining axes 17 and 26. Axis 25 is coplanar with axes 15 and 17 andlies in a plane parallel to a plane containing axes 26 and 27.

[0046] When links 11 and 12 are simultaneously pivoted about axes 14 and15, link 23 and the tool 24 pivot about axis 28 at a virtual pivot point29. Because axis 26 is coplanar with axes 16 and 17, the virtual pivotpoint 29 is constrained to lie in a plane containing axes 14 and 15.Moreover, the virtual pivot point 29 is also constrained to be inlinewith the pivots connecting link 23 to links 21 and 22. As describedabove, depending on the situation and application, these constraints cancreate problems. In particular, in medical applications, the fact thatthe virtual pivot point 29 is constrained to lie in a plane containingaxes 14 and 15 can make it difficult to provide adequate clearancebetween the manipulator and portions of the patient's body not involvedin the procedure and between the manipulator and any other equipmentinvolved in the procedure such as imaging equipment. The constraint thatthe virtual pivot point 29 be inline with the pivotal attachments oflink 23 raises difficulties when the manipulator is used in conjunctionwith imaging equipment. In particular, link 23, which supports the tool,is typically in the same plane as the image of interest and tends todistort that image.

[0047] In accordance with one aspect of the present invention, amanipulator can be provided which does not have the virtual pivot pointconstraints that are associated with the conventional arrangement ofFIG. 1. For example, FIG. 2 schematically illustrates a kinematic modelof a manipulator according to the present invention in which the virtualpivot point is not constrained to be in the same plane as the base pivotaxes 14 and 15. This manipulator is similar to that of FIG. 1 in that itincludes two parallel linkages 10 and 20A, but link 21 of linkage 20Ahas been rotated with respect to link 13 relative to its orientation inFIG. 1 so that the two links 13 and 21 are no longer aligned, i.e., sothat axis 26 is not coplanar with axes 16 and 17. Link 22 remainsparallel to link 21.

[0048] As in FIG. 1, when links 11 and 12 are pivoted about axes 14 and15, link 23 and the tool 24 which it supports pivot about axis 28 atvirtual pivot point 29. However, since axis 26 is not coplanar with axes16 and 17, axis 28 and thus the virtual pivot point 29 are spaced fromthe plane containing axes 14 and 15. This can make the manipulator ofFIG. 2 more convenient to use than the manipulator of FIG. 1 and morecomfortable for both an operator of the manipulator and a patientundergoing treatment. Depending upon whether link 21 is bent upward ordownward with respect to link 13, the virtual pivot point 29 may beabove or below the plane containing axes 14 and 15. The distance of thevirtual pivot point 29 above or below the plane can be varied by varyingthe angle between links 13 and 21 or the lengths of the various links.

[0049] In FIG. 2, links 13 and 21 are both straight members at an obtuseangle to each other, but they may have any shapes such that axis 26 isspaced from the plane containing axes 16 and 17. For example, link 21can be curved or crank shaped, as schematically shown in FIGS. 3 and 4,respectively. Moreover, link 13 is shown rigidly connected to link 21 inFIG. 2, but, alternatively, it may be rigidly connected to link 22, asschematically shown in FIG. 5. Alternatively, link 13 may remain rigidlyconnected to link 21, and an additional link rigidly connected to link22 may be pivotably connected between link 11 and link 12 parallel tolink 13. Likewise, link 21 is illustrated as being integrally formedwith link 13, but the two links may be separately formed and rigidlyconnected to each other in any suitable manner.

[0050] In FIG. 2, link 23 has a length such that the tip of the tool 24coincides with the virtual pivot point 29, but the virtual pivot point29 may be at any desired location with respect to link 23 and the tool24. If the virtual pivot point 29 represents a point on the skin of apatient which is to be contacted by the tool 24, the lower end of thetool 24 may coincide with the virtual pivot point 29. If the tool 24 isto be inserted through an incision or other opening in the body of apatient to access a location within the patient's body, the virtualpivot point 29 may be a point within the body wall of the patient aboutwhich link 23 is to be pivoted, in which case the virtual pivot point 29may coincide with a location on link 23 located above the tool 24. Ifthe tool 24 is a laser or other device which is being used to treat alocation on the patient's skin without contacting the location, thevirtual pivot point 29 may coincide with the location on the skin and bespaced from both link 23 and the tool 24. Thus, the location of thevirtual pivot point 29 with respect to link 23 and the tool 24 may varydepending upon the nature of the tool 24 and the type of procedure whichis to be performed with the tool 24.

[0051] As will be appreciated, a manipulator according to the presentinvention can be used to manipulate a wide variety of objects, but it isparticularly suitable for use in manipulating medical tools. A fewexamples of tools which can be used with a manipulator according to thepresent invention are cutting devices, needle holders, staples, forceps,clamps, probes, imaging devices, lasers, needles or other biopsydevices, devices for administering medication or other substances, orother devices for surgical, therapeutic, or diagnostic purposes.Moreover, while the present invention is described herein in connectionwith performing medical procedures, it will be readily appreciated thatit is equally applicable to other types of applications involvingmanipulators.

[0052] In the embodiment shown in FIG. 2, the virtual pivot point 29 isstill inline with the pivotal connections of the link 23 to links 21 and22. Therefore, in order for the tool 24 to contact the virtual pivotpoint 29, the tool 24 must be mounted on link 23 inline with thosepivotal connections. As noted above, this constraint can pose problemswhen the manipulator is used in conjunction with an imaging device inthat link 23 obscures the image of the relevant area. Thus, according toanother aspect of the present invention a manipulator can be provided inwhich the virtual pivot point is offset from the line defined by thepivots of link 23. As schematically shown in FIG. 6, by appropriatelyshaping the links of a manipulator, the virtual pivot point 29 can bespaced from the line defined by the pivots of link 23 supporting thetool 24. The manipulator of FIG. 6 is generally similar to themanipulator of FIG. 2, but link 12 of FIG. 2, for which axes 25, 17, and15 are coplanar, has been replaced by a link 12A having a shape suchthat axis 25 is spaced from a plane connecting axes 15 and 17. Link 11A,which is parallel to link 12A, is shown having a non-linear shapesimilar to that of link 12A, but it may have any shape such that a planecontaining axes 14 and 16 is parallel to a plane containing axes 15 and17. Except for links 11A and 12A, the arrangement of the links is thesame as in FIG. 2. The manipulator illustrated in FIG. 6 would functionidentically if it is arranged similar to the link arrangement in FIG. 5with only links 11A and 12A being substituted for links 11 and 12.

[0053] As in the previous examples, when links 11A and 12A are pivotedabout axes 14 and 15, link 23 and the tool 24 which it supports pivotabout an axis 28, which is parallel to axis 14, at a virtual pivot point29. However, due to the shape of link 12A, the virtual pivot point 29 isspaced from a line defined by the pivots of link 23. Therefore, in thiscase, the tool 24 can be supported by a tool holder 30 which is spacedforward (with reference to FIG. 6) of link 23 and still contact thevirtual pivot point 29. As will be appreciated, the virtual pivot pointcould be spaced rearward of link 23 by configuring link 12A such thataxis 25 is spaced forward of the plane connecting axes 15 and 17 andconfiguring link 11A with a complementary shape. Moreover, varying theshape of links 11A and 12A can vary the distance that the virtual pivotpoint is offset from the pivots of link 23. The spatial relationshipbetween axes 17, 25 and 15 is maintained in the spatial relationshipbetween axes 26 and 27 and the axis 28 at the virtual pivot point. Whilethe embodiment of the invention shown in FIG. 6 is also configured suchthat the links 13 and 21 are not in alignment so as to also offset thevirtual pivot point 29 from the plane of pivots 14 and 15, theembodiment of the invention shown in FIG. 6 could also be configuredsuch that links 13 and 21 are in alignment and the virtual pivot is inthe plane of pivots 14 and 15.

[0054] In accordance with another aspect of the present invention, amanipulator can be provided which is capable of moving a tool about avirtual pivot point with two degrees of freedom. Specifically, in someinstances, it may be sufficient to rotate a tool with a single degree offreedom about a single axis passing through a virtual pivot point. Inother situations, it may be desirable to also rotate a tool with anotherdegree of freedom about a second axis passing through the virtual pivotpoint, such as an axis perpendicular to the first axis. An illustrativeembodiment of a manipulator 302 capable of producing movement of a tool304 about a virtual pivot point 305 with two degrees of freedom is shownin FIG. 7. The manipulator 302 generally comprises two parallelogramlinkage mechanisms 306, 308 that move in parallel planes and are linkedtogether.

[0055] In the embodiment of the invention illustrated in FIG. 7, each ofthe two parallelogram linkage mechanisms 306, 308 comprises a 4-barlinkage. Each includes parallel front and rear vertical links 310, 312,314, 316 that at one end are pivotally connected to a base 320 and athird horizontal link 322, 324 that pivotally connects the opposite endsof the front and rear vertical links. In each mechanism, the horizontallink 322, 324 is parallel to a line defined by the base pivots of therespective pair of vertical links 310, 312 and 314, 316. Each of thevertical links 310, 312, 314, 316 is mounted to the base 320 and to itsrespective horizontal link 322, 324 for pivotal movement about twoperpendicular axes. In the illustrated embodiment this is accomplishedby at the base pivots by pivotally connecting each vertical link to acorresponding roller 326, 328. For example, vertical link 310 ispivotally connected to a roller 326 which is rotatably supported by base320. The pivotal connection to the roller 326 allows vertical link 310to rotate about axis 332 while the roller allows vertical link 310 torotate about axis 330. At the opposing end, vertical link 310 ispivotally connected to horizontal link 322 for rotation about axis 334.Horizontal link 322 is, in turn, rotatably supported such that verticallink 310 can rotate about axis 336 which is perpendicular to axis 334.The other vertical links 312, 314, 316 have similar pivotal connectionsto the base 320 and their respective horizontal link 322, 324 such thateach is rotatable with two degrees of freedom with respect to the baseand the corresponding horizontal link about two perpendicular axes. Forease of reference, besides the rotational axes for vertical link 310,only the rotational axes 337 and 338 for the connection of vertical link314 to the base and the rotational axes 342 and 344 for the connectionof vertical link 314 to horizontal link 324 are shown in FIG. 7.

[0056] As vertical links 310 and 314 are rotated respectively about axes332 and 337 through operation of their respective parallelogramlinkages, the vertical links 310 and 314 move in parallel planes. Toensure that these planes are constrained to move in parallel relation asthe vertical links 310 and 314 rotate respectively about axis 330 and338, the two parallelogram linkages 306, 308 are connected together attheir forward ends by upper and lower connector links 346 and 348. Theupper and lower connector links 346, 348 extend parallel to each otherand interconnect, in this case, vertical link 310 of the firstparallelogram linkage 306 and vertical link 314 of the secondparallelogram linkage 308. In particular, the upper connector link 346is pivotally connected adjacent one end to horizontal link 322 (andthereby vertical link 310) for rotation relative to vertical link 310about axis 336 and adjacent the opposing end to horizontal link 324 (andthereby vertical link 314) for rotation relative to vertical link 314about axis 342. Similarly, the lower connector link 348 is pivotallyconnected adjacent one end to vertical link 310 through an intermediatehorizontal link 354 for rotation about axis 350 and adjacent theopposing end to vertical link 314 through an intermediate horizontallink 356 for rotation about axis 352.

[0057] To impart some stress into the manipulator 302 and thereby reducethe free play, the manipulator illustrated in FIG. 7 includes additionallinks and connections. In particular, each of the parallelogram linkagemechanisms 306, 308 includes an intermediate horizontal link 354, 356which interconnects the two vertical links. Using the interconnectionbetween vertical link 310 and intermediate horizontal link 354 as anexample, vertical link 310 is pivotal about axes 350 and 358 relative tothe intermediate horizontal link. In this instance, the pivotal movementabout axis 350 is achieved via rotatably supporting the intermediatehorizontal link 354 at either end in a similar manner to the horizontallinks 322 and 324. As shown in FIG. 7, axis 350 is parallel to axis 336and axis 358 is parallel to axis 334. The other vertical links havesimilar pivotal connections with the respective intermediate horizontallinks. The illustrated manipulator further includes an upper support bar360 extending parallel to the horizontal links 322, 324 of the twoparallelogram linkages 306, 308 and an intermediate support bar 362 thatextends parallel to the intermediate horizontal links 354, 356.Additionally, the manipulator includes rear connector links 364, 366which interconnect vertical links 312 and 316 and horizontal links 322,324 at the rear ends of the parallelogram linkages. The rear connectorlinks 364, 366 and the upper and lower connector links 346, 348 at theforward end of the parallelogram linkages further serve the function ofrotatably supporting the horizontal links 322, 324 and the intermediatehorizontal links 354, 356.

[0058] Like the intermediate horizontal links 354, 356, the support bars360, 362 and rear connector links 364, 366 are redundant and helpintroduce more rigidity into the manipulator 302 thereby reducing freeplay. This reduction in free play is useful in surgical applications,however, it will be appreciated that the intermediate horizontal linksand support bars are not necessary parts of the present invention.Furthermore, while the illustrated embodiment produces certain pivotalmovements by rotatably supporting either end of the horizontal links andthe intermediate horizontal links, other types of pivotal connectionsbetween the various links could be used. Similarly, the upper and lowerconnector links could be connected directly to vertical links 310 and314 rather than through the horizontal links 322, 324 and intermediatehorizontal links 354, 356 as in the illustrated embodiment.

[0059] For supporting the tool 304 for rotary movement at the remotevirtual pivot point 305 with two degrees of freedom, the manipulator 302includes a tool holder link 368 that is pivotally connected to the upperconnector link 346 and pivotally connected to the lower connector link348. In the illustrated embodiment, the pivots for the tool holder link368 are at the free end of extended portions of the connector links 370,372 which extend parallel to each other and outwardly away from theforward end of the two parallelogram linkages. The pivotal connection ofthe tool holder link 368 with the upper connector link 346 permitspivotal movement about axis 374 (via yoke 376) and axis 378 (via pivotjoint 380) which intersects and is perpendicular to axis 374. Similarly,the pivotal connection of the tool holder link 368 with the lowerconnector link 348 permits pivotal movement about axis 382 (via yoke384) and axis 386 (via pivot joint 388) which intersects and isperpendicular to axis 382. With this arrangement, a tool held by thetool holder link 368 will rotate about axis 390 at the virtual pivotpoint 305 when the vertical links 310, 312 are pivoted side-to-sideabout axes 330 and 338 and the tool rotate about axis 392 at the virtualpivot point when the vertical links are pivoted front-to-back about axes332 and 333. During this pivotal movement, the upper and lower connectorlinks 346, 348 are constrained to move in parallel relation to eachother by the two parallelogram linkage mechanisms 306, 308.

[0060] In the embodiment illustrated in FIG. 7, the vertical links 310,312, 314, 316 are offset rearward such that the pivotal connection withthe intermediate horizontal links 354, 356 (and in turn the lowerconnector link 348) is not co-linear with a line defined by theconnections of the vertical links with the horizontal links 322, 324 andthe base 320. This arrangement is similar to the one degree of freedommanipulator illustrated in FIG. 6 and results in a shift of the virtualpivot point forward from a line intersecting the pivotal connections ofthe tool support link.

[0061] A further embodiment of a manipulator constructed in accordancewith the present invention is illustrated in FIG. 9. The embodiment ofFIG. 7 is over constrained and includes redundant links. In theembodiment of FIG. 9, these redundant links have been removed. Theembodiment of FIG. 9 functions in the same manner as the FIG. 7embodiment and can still be understood as being based on twoparallelogram linkage mechanisms operating in parallel that areconnected together. However, in the case of the embodiment of FIG. 9,the two parallelogram linkages share a common rear vertical link 50 anda common horizontal link 70. The intermediate horizontal links and therear connector links of the FIG. 7 embodiment have been eliminated andthere are no additional support bars in the manipulator.

[0062] Another way in which the FIG. 9 embodiment can be understood isby taking a parallelogram linkage like that shown in FIG. 2 andreplacing one of the parallel vertical links with a second parallelogramlinkage which moves in a plane perpendicular to the first parallelogramlinkage. To this end, FIG. 8a is a schematic isometric view of amanipulator, and FIG. 8b is a schematic front elevation of themanipulator pivoted sideways with respect to the vertical. Themanipulator includes a parallel linkage 40 including links 41-44. Links41 and 42, which are parallel to each other, are pivotable at theirlower ends about parallel axes 45 and 46, respectively, with the lowerends of the links being supported by a base or other suitable structuresuch that axes 45 and 46 remain stationary with respect to each other.Links 43 and 44, which are parallel to each other, are each pivotablyconnected to links 41 and 42. Link 43 is pivotably connected to link 41for pivoting about axis 47, and it is pivotably connected to link 42 forpivoting about axis 48. Link 44 is pivotably connected to link 41 forpivoting about axis 49 between axes 45 and 47, and it is pivotablyconnected to link 42 for pivoting about axis 50 between axes 46 and 48.All of axes 45-50 are parallel to each other.

[0063] Link 51 and link 52, which is parallel to link 51, extendtransversely from link 43 and link 44, respectively. Links 51 and 52remain in parallel relation as parallel linkage 40 moves from side toside in a plane and are illustrated as being rigidly connected to links43 and 44, but they may be pivotably connected to links 43 and 44 ifsome means is provided for constraining links 51 and 52 such that theymove in parallel relation to each other. Links 51 and 52 are pivotablyconnected to link 53, which supports a tool 54 at its lower end, forpivoting about axes 55 and 56, respectively, which are parallel to axis45. Axis 55 is spaced from a plane containing axes 47 and 48, and axis56 is spaced from a plane containing axes 49 and 50, while a planecontaining axes 55 and 56 is parallel to a plane containing axes 45, 47,and 49.

[0064] With this arrangement, when links 41 and 42 are simultaneouslypivoted about axes 45 and 46, as shown in FIG. 8b, link 53 and the tool54 pivot at a virtual pivot point 58 about an axis 57 which is parallelto axis 45 but is spaced from a plane containing axes 45 and 46. Thus,by combining the aspect of the invention illustrated in FIGS. 7 and 8with the aspect of the invention illustrated in FIG. 2, a manipulatoraccording to the present invention can pivot a tool about a virtualpivot point with two degrees of freedom. For example, if link 12 of FIG.2 is made a parallel linkage similar to linkage 40 of FIG. 8a, and iflinks 21 and 22 of FIG. 2 can pivot with respect to link 23 with twodegrees of freedom, then a tool can be made to pivot with two degrees offreedom at a virtual pivot point about two orthogonal axes, such as axis28 of FIG. 2 and axis 57 of FIG. 8a.

[0065] Referring again to the manipulator shown in FIGS. 9-15, thevertical link 50 is pivotably supported at its lower end by a base 55for pivoting about axis 80 and axis 81 perpendicular to and intersectingaxis 81. Two vertical links 61 and 62 extend parallel to each other andto vertical link 50. Vertical links 61 and 62 are supported by the base55 for movement parallel to link 50. Like the FIG. 7 embodiment,vertical links 61 and 62 are interconnected by parallel upper and lowerconnector links 64 and 65. Horizontal link 70 is pivotably connected atone end to link 50 for pivoting about axis 82 parallel to axis 80 andabout axis 83 perpendicular to and intersecting axis 83 and parallel toaxis 81. At its other end, link 70 is pivotably connected to the upperconnector link 64 for pivoting with respect to the upper connector linkabout axis 89 parallel to axis 82. The upper connector link is pivotallyconnected to vertical link 62 for pivotal movement about axes 88 and 89and to vertical link 61 for pivotal movement about axes 87 and 89. Thelower connector link 65 is pivotally connected to vertical link 62 forpivotal movement about axes 93 and 94 and to vertical link 61 forpivotal movement about axes 92 and 94.

[0066] As with the FIG. 7 embodiment, the upper and lower connectorlinks 64 and 65 include respective extended portions 71 and 75 whichextend parallel to each other for supporting a tool holder link 78. Thetool holder link 78 is adapted to support a tool and is connected to theupper connector link extended portion 71 for pivotal movement about axis90 parallel to axis 81 and about axis 91 (via yoke 73) perpendicular toand intersecting axis 90. The tool holder link 78 is connected to thelower connector link extended portion 75 for pivotal movement about axis95 and about axis 96 (via yoke 76) perpendicular to and intersectingaxis 95. The yokes 73 and 76 are pivotally connected to the ends of theextended portions of the upper and lower connector links 71 and 75 so asto produce the pivotal movement about axes 90 and 95.

[0067] The various links can be configured in a wide variety of ways andresult in kinematically equivalent arrangements, all of which areincluded in the scope of the present invention. Thus, the structureshown in FIG. 9 is but one example of a manipulator according to thepresent invention. In the illustrated embodiment, vertical link 50includes lower and upper yokes 51, 52 secured to opposite ends of thelink. The lower yoke 51 is connected to a yoke 56 mounted on the base 55by a spider 56 a to define a universal joint pivotable about axes 80 and81. The upper yoke 52 is connected to a yoke 70 a on the end of link 70by a spider 70 b to define another universal joint pivotable about axes82 and 83.

[0068] Vertical links 61 and 62 are similar in structure to link 50,each including a yoke at either end. The lower yoke of vertical link 61is pivotably connected to a first end of a lower pivotal support 63 forpivoting about axis 85, and the upper yoke is pivotably connected to oneend of the upper connector link 64 for pivoting about axis 87 which isparallel to axis 85. The lower yoke of link 62 is pivotably connected tothe second end of the lower pivotal support 63 for pivoting about axis86, which is parallel to axis 85, and the upper yoke of link 62 ispivotably connected to the second end of the upper connector link 64 forpivoting about axis 88, which is parallel to axis 85. The lower pivotalsupport 63 is pivotably supported by a yoke 57 mounted on the base 55for pivoting about axis 84, which is parallel to axis 89. The lowerconnector link 65 includes two yokes 65 a. One of the yokes 65 a ispivotably connected to vertical link 61 and the other yoke 65 a ispivotably connected to vertical link 62.

[0069] When vertical link 50 is pivoted about axis 80 and the verticallinks 61 and 62 is pivoted about axis 84, as shown, for example, by FIG.11, the manipulator behaves like the kinematic model of FIG. 2, with theinterconnected vertical links 61 and 62 functioning as a single rigidlink corresponding to link 12 of FIG. 2. As a result, the tool holderlink 78 and the tool 79 pivot at a virtual pivot point 99 about axis 97,which is parallel to axis 84. When vertical link 50 is pivoted aboutaxis 81 and vertical links 61 and 62 are pivoted about axes 85 and 86,respectively, as shown, for example, by FIGS. 14 and 15, the manipulatorbehaves like the kinematic model of FIGS. 8a and 8 b, and link 78 andthe tool 79 pivot at the virtual pivot point 99 about axis 98, which isparallel to axis 81 and perpendicular to axis 97 and intersects axis 97at the virtual pivot point 99. The upper connector link extended portion71, which corresponds to link 21 of FIG. 2, is not aligned with thehorizontal link 70, so the virtual pivot point 99 is spaced from a planecontaining axes 85 and 86.

[0070] The tool 79 may remain stationary with respect to the tool holderlink 78, or the tool holder link 78 may include structure which enablesthe tool 79 to be manipulated with respect to the tool holder link 78with one or more degrees of freedom. For example, the tool holder link78 may be capable of translating the tool 79 in its axial direction, ofrotating the tool 79 about its longitudinal axis, and of pitching and/oryawing the tool 79 with respect to the tool holder link 78.

[0071] Vertical links 50, 61, and 62 are shown pivotably supported by acommon base 55, but they may be mounted on separate members. The base 55is shown sitting on a crank-shaped support 58 having a support pin 59,the upper end of which represents the location of the virtual pivotpoint 99. However, the pin 59 performs no function in the operation ofthe manipulator and is present merely to make the location of thevirtual pivot point 99 easier to identify in this figure. In actual use,the manipulator can be mounted on any convenient support member, whichmay be stationary or movable. For example, the manipulator may bemounted on a wall, a ceiling, a support stand, a movable gantry, anoperating table, an imaging device or other medical device with whichthe manipulator is to be used, or the distal end of another manipulator.

[0072] In FIG. 9, the vertical links 61 and 62 are located betweenvertical link 50 and the tool holder link 78. Alternatively, thepositions of vertical link 50 and the vertical links 61 and 62 can beinterchanged, with vertical link 50 located between vertical links 61and 62 and tool holder link 78.

[0073] The links of a manipulator according to the present invention canbe of fixed length, or they can be of adjustable length to enable thelocation of the virtual pivot point to be adjusted without having tomove the entire manipulator. An adjustable link can have a variety ofstructures. For example, it can be a member with telescoping orotherwise overlapping portions and which can be lengthened or shortenedeither by hand or by an actuator, such as a motor or a cylinder,connected between the different telescoping portions of the link.

[0074] Additionally, the extended portions 71, 75 of the upper and lowerconnector links are shown centered between the pivots of the verticallinks 61 and 62. However, this is not necessary. The extended portions71, 75 only need to be connected to the upper and lower connector links64, 65 in a plane parallel to a plane containing link vertical link 50.By combining this possible linear translation of the attachment pointsof the extended portions 71, 75 with telescoping extended portions andangular variations between the extended portion 71 of the upperconnector link and the horizontal link 70, three dimensionaltranslational motion can be defined to allow the translation of thevirtual pivot pivot 99 to any point within the reach of the mechanism.

[0075] The manipulator of FIG. 9 can be operated by exerting a force onone or more of the vertical links 50, 61, and 62 to cause the link topivot about its lower end. The manipulator can be operated manually orby actuators employing electrical, pneumatic, or hydraulic power, forexample. When the manipulator is operated manually, one of the links,such as vertical link 50, can be directly grasped by the hand of a user,or a lever, a wheel, a crank, or other manually operable member can bemechanically coupled to one or more of the links to pivot the link withone or more degrees of freedom. Additionally, the manipulator configuredsuch that it can be locked in position either by the actuators or bybrakes or another type of mechanical lock.

[0076] Actuators for driving the manipulator can be connected to themanipulator at a variety of locations to exert a torque on a link aboutone or more of the rotational axes. For example, as shown in FIG. 16,motors 110 and 111, which may include a reduction gear, can be mountedon each yoke 51, 56 of the universal joint at the lower end of verticallink 50. In this example, each motor 110, 111 has an output shaftcoaxially secured to one leg of the spider 56 a of the universal jointand a housing, with respect to which the output shaft can rotate,secured to the yoke so that when the motor is operated, the spider 56 aand the yoke 51 or 56 are made to undergo relative rotation about theaxis of the output shaft. When motor 110 is operated, vertical link 50pivots about axis 80, and when motor 111 is operated, vertical link 50pivots about axis 81. Alternatively, motors can be mounted on the loweryoke of one or both of vertical links 61 and 62 to pivot these linksabout axes 85 and 86, and a motor can be connected to lower pivotalsupport rod 63 to rotate the parallel linkage 60 about axis 84.

[0077] The motors may be controlled in response to signals from asuitable input device. In particular, the manipulator of the presentinvention can be used as a slave robot in a master-slave robotic system.In such a system, a surgeon/operator provides position input signals tothe “slave” manipulator via a master or haptic interface which operatesthrough a controller or control console. Specifically, through the useof an input device on the haptic interface such as a joystick, footpedal or the like, the surgeon indicates the desired movement of thetool held by the manipulator. The haptic interface relays these signalsto the controller which, in turn, applies various desired predeterminedadjustments to the signals prior to relaying them to the slavemanipulator. Any haptic interface can be used to control the manipulatorvia the controller. Other input devices such as a keyboard, a tapememory or other storage device, a mouse, a digitizer, a computer glove,or a voice operated controller could also be used.

[0078] Based on the signals provided by the controller, the manipulatorexecutes the desired movement or operation of the tool. Thus, anydesired dexterity enhancement can be achieved by setting up thecontroller to perform the appropriate adjustments to the signals sentfrom the haptic interface. For example, this can be accomplished byproviding the controller with software which performs a desireddexterity enhancement algorithm. Software dexterity enhancementalgorithms can include position scaling, force scaling, tremor filteringand gravity compensation. These and other examples of possiblealgorithms are well known in the field of robotics and described indetail in published literature.

[0079] The various actuators and/or the tool holder link can also beequipped with sensors for sensing the forces or torques applied thereonso as to enable a determination of the forces and torques applied to thetool. This information can again be used in a feedback control loop tothe controller, for example to allow force feedback to the input deviceof the haptic interface. Of course, any known method for measuringforces and/or torques can be used, including, for example, foil type orsemiconductor strain gauges or load cells. The forces also could bedisplayed on a display device for an operator of the manipulator.Additional details regarding input devices, controllers and actuatorssuitable for manipulators to be used in medical imaging environments isdisclosed in commonly assigned U.S. application Ser. No. 09/442,966entitled “Medical Manipulator For Use With An Imaging Device” which ishereby incorporated by reference.

[0080] In the manipulator embodiments shown in FIGS. 2-16, parallelogrammechanisms comprising four bar linkages are employed to constraincertain links to move in parallel relation as the manipulator swingsback and forth to move a tool in space. However, as will be appreciatedby those skilled in the art, parallelogram linkages other than four-barlinkages can perform a similar function. For example, another embodimentof a manipulator constructed in accordance with the present invention isshown in FIGS. 17-23. The embodiment of the invention shown in FIGS.17-23 functions in the same manner as the embodiment shown for examplein FIG. 7, however, instead of using two parallel four bar linkages thatare linked together the embodiment of the invention shown in FIGS. 17-23utilizes two parallel gear linkage mechanisms (referenced herein asfirst and second parallel gear linkage mechanisms).

[0081] Each of the gear linkage mechanisms includes a vertical link 150,151. The vertical links 150, 151 are parallel to each other and, in thiscase, are identical. The lower end of the vertical link 150 of the firstgear linkage mechanism is supported by a lower horizontal rod 152 forpivoting about an axis 170. The lower horizontal rod 152 is, in turn,pivotably supported by a base 154 for pivoting about an axis 171perpendicular to and intersecting axis 170. In a similar manner, thelower end of the vertical link 151 of the first gear linkage mechanismis supported by a lower horizontal rod 153, which is parallel to thelower horizontal rod 152 of the first gear linkage mechanism, forpivoting about an axis 172 (which is parallel to axis 170). The lowerhorizontal rod 153 is pivotably supported by the base 154 for pivotingabout an axis 173 which is parallel to axis 171 and intersects axis 172.The base 154 is shown mounted on a support 58 like the one illustratedin FIG. 9, but the manipulator may be supported in any other convenientmanner, such as in the ways described with respect to FIG. 9.

[0082] The upper end of the vertical link 150 of the first gear linkagemechanism is pivotable with respect to an upper horizontal rod 155,which is parallel to the lower horizontal rod 152 of the first gearlinkage mechanism, for pivoting about an axis 174, which is parallel toaxis 170. Again, in a similar manner, the upper end of the vertical link151 of the second gear linkage mechanism is pivotable with respect to anupper horizontal rod 156, which is parallel to the lower horizontal rod155, for pivoting about an axis 176, which is parallel to axis 172. Thetwo upper horizontal rods 155 and 156 are pivotably connected to anupper crosspiece 157 which functions as an upper connector link (similarto the upper connector link 346 of the FIG. 7 embodiment) between thetwo gear linkage mechanisms. The upper horizontal rod 155 of the firstgear linkage mechanism is pivotable with respect to the upper crosspiece157 for pivoting about axis 175, which is parallel to axis 171. Theupper horizontal rod 156 of the second gear linkage mechanism ispivotable with respect to the upper crosspiece 157 for pivoting aboutaxis 177, which is parallel to axis 173.

[0083] The first gear linkage mechanism further includes a yoke 160which is parallel to the lower horizontal rod 152. The yoke 160 ispivotably connected to the vertical link 150 between its upper and lowerends for pivoting about axis 180, which is parallel to axis 170. Thesecond gear linkage mechanism also includes a yoke 161 which is parallelto the yoke 160 of the first gear linkage mechanism. The yoke of thesecond gear linkage mechanism is pivotably connected to the verticallink 151 between its upper and lower ends for pivoting about an axis 182which is parallel to axis 172. A lower crosspiece 162, which is parallelto the upper crosspiece 157, extends between and is pivotably connectedto the yokes 160 and 161. Like the upper crosspiece 157, the lowercrosspiece functions as a connector link between the two gear linkagemechanisms (similar to the lower connector link 348 of the FIG. 7embodiment). The lower crosspiece 162 is pivotable with respect to theyoke 160 of the first gear linkage mechanism about axis 181, which isparallel to axis 171. Similarly, the lower crosspiece 162 is alsopivotable with respect to the yoke 161 of the second gear linkagemechanism about axis 183, which is parallel to axis 173. The upper andlower crosspieces 157, 162 constrain the vertical links 150, 151 of thetwo gear linkage mechanisms such that the vertical links remain inparallel relation as they respectively pivot about axis 171 and axis173.

[0084] For supporting a tool 166, the manipulator illustrated in FIGS.17-23 includes a tool holder link 165 which is connected to the two gearlinkage mechanisms via extended portions 158, 163 of the upper and lowercrosspieces. Specifically, the extended portion 158 of the uppercrosspiece 157 has a yoke 159 at its free end. The yoke 159 is pivotablyconnected to the extended portion 158 for pivoting about an axis 184,which is parallel to axis 171. The yoke 159 is also pivotably connectedto the tool holder link 165 for pivoting about an axis 185 which isperpendicular to axis 184. The extended portion 163 of the lowercrosspiece 162 extends parallel to the extended portion 158 of the uppercrosspiece and pivotally supports a yoke 164 at its free end forrotation about axis 186, which is parallel to axis 184. The yoke 164 isalso pivotably connected to the tool support link 165 for pivoting aboutaxis 187, which is perpendicular to axis 186 and parallel to axis 185.

[0085] The upper horizontal rod 155, 156 of each gear linkage mechanismis constrained to move in parallel relation to the lower horizontal rod152 and 153 of each mechanism by a gear train comprising an odd numberof gears. In the illustrated embodiment, each gear linkage mechanismincludes three gears 200-202, 205-207. On the vertical link 150 of thefirst gear linkage mechanism, a first lower gear 200 is secured to thelower horizontal rod 152. The lower gear 200 is concentric with respectto axis 170 so that the vertical link 150 can rotate with respect to thelower gear 200 about axis 170. A second upper gear 201 is secured to theupper horizontal rod 155 concentrically with axis 174 and is rotatablewith respect to the vertical link 150 about axis 174. A thirdintermediate gear 202 is pivotably mounted on the vertical link 150between and in mesh with the upper and lower gears 201 and 202. Therotational axis of the intermediate gear 202 is shown coinciding withaxis 180, but the location of its rotational axis is not critical.Lower, upper and intermediate gears 205-207 are mounted on the verticallink 151 of the second gear linkage mechanism in the same manner. Thereduction ratios of the gears are selected so that, for example, whenthe vertical link 150 of the first gear linkage mechanism pivots withrespect to the lower horizontal rod 152 about axis 170 in a firstrotational direction by an angle ox, the upper horizontal rod 155 willrotate with respect to link 150 about axis 174 in the oppositerotational direction by the same angle α. Thus, the lower and upperhorizontal rods 152, 155 of the first gear linkage mechanism remainparallel to each other. The reduction ratios of the gears 205-207 forthe second gear linkage mechanism are selected in a similar manner.

[0086] As shown in FIG. 19, which is a side elevation of the manipulatorof FIG. 17 pivoted backwards from the position shown in FIG. 17,pivoting the vertical links of the two gear linkage mechanisms aboutaxes 170 and 172 causes the tool holder link 165 and the tool 166 topivot at a virtual pivot point 192 about an axis 190 spaced from a planecontaining axes 171 and 172. In this respect, the manipulator shown inFIG. 17 functions similar to the embodiment shown in FIG. 2 with thevertical links 150, 152 of the parallel gear linkage mechanismsfunctioning as a single link and the gear trains performing the functionof maintaining the upper and lower horizontal rods in parallel relation.When the vertical links 150 and 151 are simultaneously pivotedside-to-side about axes 171 and 173, as shown, for example, in FIGS.21-23, the tool holder link 165 and the tool 166 pivot at the virtualpivot point 192 about an axis 191 which is perpendicular to andintersects axis 190 at the virtual pivot point 192. Thus, the tool 166can be pivoted with two rotational degrees of freedom about the virtualpivot point 192. When performing the side-to-side movement, themanipulator can be considered like the kinematic model of FIG. 7, withthe vertical links 150 and 151 functioning like links 41 and 42 of FIG.7, the upper and lower crosspieces 157 and 162 functioning like links 43and 44 of FIG. 7, the extended portion of the upper crosspiece 158 andits yoke 159 functioning like link 51 of FIG. 7, the extended portion ofthe lower crosspiece 163 and its yoke 164 functioning like link 52 ofFIG. 7, and the tool holder link 165 functioning like link 53 of FIG. 7.As will be appreciated, the manipulator of FIGS. 17-23 can be driven byhand or by a motor or other actuator in a manner similar to thatdescribed with respect to FIG. 16.

[0087] In FIGS. 17-23, the upper and lower gears 200, 201, 205, and 206of the two gear linkage mechanisms are in the form of sectors of acircle. Each of the intermediate gears 202 and 207 is in the form acomplete circle. However, the upper and lower gears may also becompletely circular, and the intermediate gears 202 and 207 may eachcomprise sectors instead of a complete circle. In the illustratedembodiment, the gears of each gear train have the same diameter.However, the gears can have different diameters as long as therotational angle of the upper gear 201 and 206 of each gear linkagemechanism is equal and opposite to the rotational angle of the lowergears 200 and 205 of each gear linkage mechanism when the vertical links150 and 151 rotate with respect to the lower gears. For example, theupper and lower gears may have the same diameter, and the intermediategear may have a different diameter. In addition, the number of gears oneach link is not limited to three. In general, any odd number of gearsgreater than or equal to three can perform the desired function.

[0088] Mechanisms other than gears can be used to constrain, forexample, the upper and lower horizontal rods 155 and 152 of themanipulator shown FIG. 17 to move in parallel relation. For example, thegears can be replaced by rollers that are in rolling contact with eachother. Alternatively, the intermediate gear 202 on the vertical link maybe omitted, and the upper and lower gears can be replaced by sprockets210 connected to each other by a chain 211 so as to produce a parallelchain linkage mechanism, as shown in FIG. 24, or by pulleys 215connected to each other by a belt or cable 216 so as to produce aparallel mechanical belt or cable linkage mechanism, as shown in FIG.25. In FIG. 24, a lower sprocket 210 is secured to the lower horizontalrod 152, 153 of each parallelogram mechanism, and an upper sprocket 210is secured to the upper horizontal rod 155, 156 of each parallelogrammechanism. The lower end of the vertical link 150, 151 of eachparallelogram mechanism is pivotable with respect to the correspondinglower sprocket 210, and the upper end of the vertical link 150, 151 ispivotable with respect to the corresponding upper sprocket 210. In FIG.25, a lower pulley 215 is the lower horizontal rod 152, 153 of eachparallelogram mechanism, and an upper pulley 215 is secured to the upperhorizontal rod 155, 156 of each parallelogram mechanism. The lower endof the vertical link 150, 151 of each parallelogram mechanism ispivotable with respect to the corresponding lower pulley 215, and theupper end of the vertical link 150, 151 is pivotable with respect to thecorresponding upper pulley 215.

[0089] With the manipulator embodiment shown in FIG. 17, the pivot axes170, 172, 174, 176, 180, and 182 associated with the vertical link ofeach parallelogram mechanism lie in the same plane, so the virtual pivotpoint 192 is aligned with a plane containing axes 185 and 187. Avariation of the FIGS. 17-23 embodiment is shown in FIGS. 26 and 27.With the embodiment of the invention shown in FIGS. 26 and 27, thevertical links 150 and 151 of FIG. 17 have been replaced by verticallinks 220, 221 which have a shape such that axes 180 and 182 are spacedfrom a plane containing the other rotational axes 170, 172, 174, and 176associated with the vertical links. The arrangement of the various linksand rods is otherwise the same as in FIG. 17. Similar to the embodimentshown in FIG. 6, this shape of the vertical links 220 and 221 enablesthe virtual pivot point 192 to be spaced from a plane containing theaxes 185 and 187 defined by the pivotal connections of the yokes 159,164 of the extended portions 158, 163 of the upper and lower crosspieces157, 162 to the tool holder link 165. Accordingly, the tool 166 can bemounted on the tool holder link 165 in a location other than a planecontaining axes 185 and 187 and still contact the virtual pivot point192. For example, the tool 166 can be mounted such that it is spacedforward of the plane containing axes 185 and 187 so that it does notinterfere with imaging operations and where the yokes 159 and 164 orother portions of the manipulator do not interfere with movement of thetool 166.

[0090] In accordance with a further aspect of the present invention, themanipulator can include a tool holder 410 for holding and moving a toolwith one or more degrees of freedom while minimizing contact between thetool holder and the tool. As stated above, a tool which is supported bya manipulator according to the present invention can be selected from awide variety of devices, both for medical and non-medical purposes. FIG.28 illustrates a portion of a manipulator according to the presentinvention having the structure shown in FIG. 26 which includes a toolholder 410 configured to hold a biopsy needle 412. The tool holder 410is mounted on the link 165 and can translate the needle 412 in itslengthwise direction with respect to the link 165.

[0091] To this end, as shown in FIGS. 28-30, the tool holder 410includes a cartridge 414 having a movable carriage 416 which can engagethe proximal end of the needle 412 and can move in the lengthwisedirection of the needle to translate it toward or away from a patient.The cartridge 414 is detachably mounted on a drive unit 420 whichcontains a motor or other drive mechanism which can be operativelycoupled to the carriage 416 to translate the carriage in the lengthwisedirection of the needle 412. The drive unit 420 includes a pair ofaligned shafts or axles 422 which are pivotably supported by a yoke 424secured to link 165. The yoke 424 includes a motor or other drivemechanism which can controllably pivot the drive unit 420 about therotational axes of the axles 422 to a desired angle. However, when thetool holder 410 is used with a manipulator according to the presentinvention, the motor is typically not operated so that the drive unit420 remains at a constant angle with respect to the yoke 424, with thelongitudinal axis of the needle 412 aligned with the virtual pivot point192 of the manipulator.

[0092] The illustrated tool holder 410 is just one example of manypossible devices for supporting a needle, but it is particularlyadvantageous because it minimizes the number of components which aresubject to contamination during a medical procedure using the needle412. In particular, the only portion of a tool holder according to thepresent invention which comes into direct contact with a needle or othermedical tool is the replaceable cartridge. The motors for translatingthe carriage 416 or for rotating the drive unit 420 are protected fromcontamination, so the drive unit and the yoke 424 typically do not needto be sterilized between uses. On the other hand, the cartridge 414 andthe needle 412, which may be subject to contamination, can be readilyreplaced as a single unit after a single use, to be either sterilized ordiscarded. The cartridge does not require high precision for itsmanufacture nor does it require high strength, so it can beinexpensively manufactured to enable it to be economically discarded, ifdesired, after a single use. The other portions of the tool holder aresubstantially free from contamination, so they can be reused with a newcartridge without having to be sterilized between uses.

[0093] As shown in FIGS. 33-35, the cartridge 414 includes an elongatedcarriage guide 426 along which the carriage is movable in a linear pathin a lengthwise direction of the guide. The illustrated carriage guide426 has a generally U-shaped transverse cross section with two elongatedguide flanges 428 extending transversely from its upper end as shown inFIG. 35. The carriage guide 426, however, may have any desired shapewhich enables it to guide the carriage 416. An elongated slot 430through which a drive pin 432 of the drive unit 420 can pass extends inthe lengthwise direction of the bottom surface of the carriage guide426. An end plate 434 is secured to the lower end (the end closest to apatient during use) of the carriage guide 426 as shown in FIGS. 33 and34.

[0094] The end plate 434 includes a needle guide for guiding a portionof the needle 412 as it translates along the carriage guide 426. Theillustrated needle guide comprises a notch 436 formed in the end plate434 through which the needle 412 can slidably pass. The notch 436 may beequipped with a retainer such as a clip 438 which can pivot between anopen position in which the needle 412 can be easily inserted into orremoved from the notch 436 and a closed position in which the clip 438prevents the removal of the needle 412 from the notch 436.

[0095] The carriage 416 can have any shape which enables it to translatealong the carriage guide 426 while engaging a needle 412 or othermedical tool. The illustrated carriage 416 has a pair of flanges 440 atits open end extending in its lengthwise direction which are shaped tofit around the guide flanges 428 on the carriage guide 426 to permit thecarriage 416 to slide along the carriage guide 426 along a linear path.The carriage 416 can engage the needle 412 so as to be capable ofexerting a drive force on the needle 412 in its lengthwise direction toinsert the needle 412 into or retract it from a patient's body.

[0096] The manner in which the carriage 416 engages the needle 412 canbe chosen in accordance with the structure of the needle. As shown inFIG. 33, the illustrated needle 412 is a commercially availableintroducer needle including an elongated hollow shank 442 and anengaging portion in the form of an enlarged head 444 molded around orotherwise secured to the proximal end (the end remote from a patient) ofthe shank. The illustrated carriage 416 is adapted to hold the needle412 by its head 444. The carriage 416 includes a recess 446 which issized to receive the head 444 of the needle 412. The lengthwise endwalls 448 of the recess 446 can press against the end faces of the head444 of the needle 412 to exert a force on the head in the lengthwisedirection of the needle. Alternatively, the side walls of the recess 446may fit snugly around the head 444 to transmit a force to the head inthe longitudinal direction of the needle 412 by friction.

[0097] A retainer in the form of a clip 450 on the carriage 416 can bepivoted between an open position shown in FIG. 33 in which the needle412 can be installed on or removed from the carriage and a closedposition in which the clip 450 fits over the head 444 of the needle 412to resist removal of the needle. One of the end walls 448 of thecarriage 416 includes a notch 452 communicating with the recess 446through which the shank 442 of the needle 412 can pass. The carriage 416may hold the needle 412 in any other suitable manner. For example, itmay include jaws or fingers which can grasp either the shank 442 or thehead 444 of the needle 412. As another example, if the head 444 of theneedle 412 has a varying outer diameter, a reduced diameter portion ofthe head may be disposed in the notch 552, and portions of largerdiameter adjoining the reduced diameter portion may be disposed outsideof the notch on either side of it to prevent lengthwise movement of theneedle 412 with respect to the carriage 416, with one of the largerdiameter portions disposed in the recess 446 and the other disposedoutside the recess. If the needle 412 is intended to house anothermember, such as an obturator, the recess 446 may be made large enough toreceive a head or other portion of the member housed in the needle.

[0098] As will be appreciated by those skilled in the art, when adifferent type of tool is being held by the tool holder 410, thecarriage 416 may be modified to engage the tool in a different mannerfrom that shown in the figures. However, the illustrated arrangement canbe used for any tool having an elongated shank and an enlargedengagement portion, such as a head, hub, collar, flange, or knobattached to the shank. Moreover, the cartridge can be adapted to permitthe tool to be released after the tool is set in a particular position.

[0099] The cartridge 414 is preferably readily detachable from the driveunit 420 to permit the cartridge to be easily installed and replaced.Any convenient method of attaching the cartridge 414 to the drive unit420 can be employed. In the illustrated cartridge 414, the end plate 434is equipped with a hole 454 through which an engagement pin 456 of thedrive unit 420 (FIG. 31) can pass. An elastically deformable clip 460which can detachably engage a flange 458 on the opposing end of thedrive unit 420 (FIGS. 31 and 32) is mounted on the opposite end of thecarriage guide 426.

[0100] In order to prevent the cartridge 414 from being reused with morethan one patient by simply replacing the needle 412 without thecartridge being sterilized, the cartridge may be structured so that aneedle cannot be removed from the cartridge without rendering thecartridge unusable. For example, one or both of the clips 438 and 450for retaining the needle 412 in the cartridge 414 may engage thecartridge when the clip is in its closed position in a manner such thata portion of the clip or a portion of the cartridge breaks off when theclip is opened, making it impossible to again secure the clip in aclosed position and secure the needle to the cartridge. Such a breakableportion may be in the form of a flange, a claw, a head, etc., which issnap-engageable with another member when the clip is in its closedposition and which breaks off when the clip is opened.

[0101] The drive unit 420 can have any structure which enables it toexert a drive force on the carriage 416 in a lengthwise direction of theneedle 412 to cause the carriage to translate along the carriage guide426. As shown in FIGS. 31-32, the illustrated drive unit 420 includes aframe 462 which supports a drive mechanism. The illustrated drivemechanism includes a lead screw 464 which engages with a movable nut 465having a drive pin 432 projecting from its upper surface for detachableengagement with the carriage 416. The carriage 416 may engage the pin432 on the drive unit 420 in any convenient manner. In the illustratedembodiment, the carriage 416 includes a recess 466 in its bottom surfacefor engagement with the pin 432. The nut 465 can be prevented fromrotating as it translates along the lead screw 464 by the sides of theframe 462 or by a guide member, such as a rod, slidably engaging withthe nut 465. The lead screw 464 can be rotated about its axis by anysuitable drive source, such as by an electric motor 468 drivablyconnected to the lead screw 464 by a gear unit 470. When the motor 468is driven, the lead screw 464 is rotated about its axis to translate thenut 465 along the lead screw 464 and move the carriage 416 of thecartridge 414 either toward or away from a patient's body. A fewexamples of other suitable drive mechanisms for translating the carriage416 along the carriage guide 426 include a belt and pulley drive, alinear motor, or a pneumatic or hydraulic cylinder.

[0102] The moving parts of the drive unit 420 are preferably enclosed toprotect them from contamination and to prevent them from contaminating apatient. As shown in FIG. 30, the illustrated drive unit 420 includes acover 472 which surrounds all the moving parts except for the pin 432 ofthe nut 465, which extends through an elongated slit 474 in the topsurface of the cover parallel to the lead screw 464. The portion of thecover 472 in which the slit 474 is formed may be made of a flexiblematerial so that the slit is substantially closed except in the regionimmediately surrounding the pin 432 where the pin forces the slit 474open.

[0103] The drive unit 420 is preferably pivotably supported by the yoke424 for pivoting about a pitch axis which is transverse (e.g.,perpendicular) to the axis of the needle 412. The illustrated yoke 434includes a pair of legs 476 separated by a cavity 478 for receiving thedrive unit 420 when the drive unit is in an initial position ash shownin FIG. 30. The drive unit 420 may be pivoted about the pitch axismanually, or the yoke 424 or the drive unit may be equipped with a drivemechanism for exerting a rotary drive force on the drive unit about thepitch axis. For example, the illustrated yoke 424 is equipped with anelectric motor 480 (FIGS. 29 and 30) which is operatively connected toone of the axles 422 of the drive unit 420 by a gear unit, such as aworm gear unit including a worm 482 secured to the output shaft of themotor 480 and a worm gear 484 secured to the axle 422. When the motor480 is operated, the entire drive unit 420 can be pivoted about thepitch axis to a desired angle. In FIG. 29, the drive unit 420 is shownpivoted clockwise about the pitch axis so that the proximal end of theneedle 412 is raised above the yoke 424, but the drive unit may berotated in the opposite direction so that the proximal end of the needle412 is positioned below the yoke. The drive unit can have any desiredrange of rotation about the pitch axis. The greater the range ofrotation about the pitch axis, the less the entire tool holder 410 needsto be moved to obtain a desired angle of the needle 412 with respect toa patient's body. In the present embodiment, the drive unit can berotated about the pitch axis by approximately ±115° from its initialposition (i.e., with the needle parallel to the longitudinal axis of theyoke), but a greater range of rotation may be employed. For example, thedrive unit 420 may be rotatable by 360° around the pitch axis.

[0104] In some situations, it may be convenient to dispense a drug orother substance to a patient during use of the needle 412. Therefore,the cartridge 414 may be equipped with one or more devices fordispensing a local anesthetic, an antiseptic agent, or other substanceto a patient when the needle 412 is being inserted into the patient'sbody. As shown in FIG. 33, the illustrated cartridge 414 is equippedwith first and second dispensing units 486 and 488 disposed on oppositewidthwise sides of the carriage guide 426 near the end plate 434. Thedispensing units, however, can be mounted in any convenient location onthe cartridge, drive unit or yoke. The first dispensing unit 486comprises an applicator for applying a liquid to the skin of a patient,while the second dispensing unit 488 comprises an injector foradministering a percutaneous injection of a substance to a patient.

[0105]FIGS. 36 and 37 are schematic cross-sectional views of examples ofthe two dispensing units 486 and 488, respectively. As shown in FIG. 36,the first dispensing unit 486 includes a reservoir 490 containing aliquid 492 to be applied to a patient's skin. An absorbent wick 494extends from the interior of the reservoir 490 where it contacts theliquid 492 through an opening 495 of the reservoir 490 to its exterior.When not in use, the outer end of the wick 494 may be covered by a capor other suitable member to prevent it from drying out. The liquid 492is drawn by the wick 494 to the outer end of the wick, which can beplaced against a patient's skin to transfer the liquid 492 from thereservoir 490 to the skin, and the tool holder 410 can be moved along adesired path to swab the patient's skin with the liquid. The liquid 492in the reservoir 490 can be any substance suitable for topicalapplication. For example, it may be PVD iodine or other antiseptic agentfor use in cleansing a patient's skin in the region into which theneedle 412 is to be inserted. Devices other than a wick 494 can be usedto transfer liquid 492 from the reservoir 490 to the patient's skin in agradual manner, such as a roller ball similar to that used in aballpoint pen or a spring-loaded valve which can open when pressedagainst the patient's skin.

[0106] As shown in FIG. 37, the second dispensing unit 488 includes ahousing having a first chamber 496 containing a first movable piston 497and a second chamber 498 adjoining the first chamber 496 and containinga second movable piston 499 coupled to the first piston 497 so that thetwo pistons can move together. The first chamber 496 is equipped with afluid port 500 through which a drive fluid can be introduced underpressure into the first chamber. The second chamber 498 is equipped withan orifice 502 opening onto the exterior of the housing through which afluid to be administered to a patient can be discharged under pressure.When not in use, the orifice 502 may be closed by a cap, a stopper,sealing tape, or other suitable member to prevent fluid from leakingfrom the second chamber 498. The drive fluid for driving the firstpiston 497 can be either a gas or a liquid, a few examples of suitabledrive fluids being air, CO₂, and water.

[0107] Prior to use, the second chamber 498 is filled with a fluid(usually a liquid but possibly a gas) to be administered to a patient,which may be any substance suitable for percutaneous injection during amedical procedure involving a needle 412 or other medical tool. Forexample, the fluid may be Lidocaine or other local anesthetic forpreventing pain in the region into which the needle is to be inserted.To inject the fluid into a patient, the cap or other cover is removedfrom the orifice 502, and the tool holder 410 is moved to a position inwhich the orifice is pressed against or is in close proximity to thepatient's skin. The drive fluid is then introduced under pressure intothe right side of the first chamber 496 through fluid port 500 to drivethe first and second pistons 497 and 499 to the left in FIG. 38. As thesecond piston 499 moves to the left, it discharges the fluid through theorifice 502 and through the patient's skin into his body.

[0108] The tool holder 41 0 of the present invention can have anextremely compact design, so it can support and manipulate a medicaltool inside tight spaces in which it would be difficult or impossiblefor a human operator to position a tool or in environments which wouldbe unsafe for a human operator. In particular, the manipulator can holda medical tool with respect to a patient inside medical imagingequipment, such as CT (computer tomography) equipment, conventionalx-ray equipment, or magnetic resonance imaging equipment, whichequipment often has a very small clearance surrounding a patient's bodyduring imaging. Therefore, the tool holder enables the position of amedical tool with respect to a patient to be adjusted while imaging istaking place and makes it unnecessary to remove the patient from theimaging equipment each time the position of the tool needs to beadjusted. For this reason, the medical tool can be positioned quicklyand accurately, enabling a medical procedure to be performed with thetool efficiently and economically with less stress on the patient. Theability of the tool to be rapidly positioned is particularlyadvantageous when the tool is being positioned in or near the patient'schest and the patient is holding his breath.

[0109] As will be appreciated, the tool holder 410 can be configured tohold a wide variety of medical tools both for therapeutic and diagnosticpurposes, a few examples of which are biopsy needles, biopsy guns,catheters, various probes including cryo probes and radio frequencyprobes, lasers, laser hyperthermia devices, cameras, and needles foradministering various substances, such as biotherapeutic agents,alcohol, or radioactive pellets, to the interior of a patient's body. Inaddition to tools which are inserted into a patient's body, the toolholder can be used to hold tools which are normally utilized on apatient's exterior. Moreover, the tool holder can be operated in amaster-slave mode, a fully robotic mode, or a semi-robotic mode in whichsome of the motions of the tool holder are controlled by input commandsfrom an operator and other motions are controlled automatically.

[0110] All of the references cited herein, including patents, patentapplications, and publications, are hereby incorporated in theirentireties by reference.

[0111] While this invention has been described with an emphasis uponpreferred embodiments, it will be obvious to those of ordinary skill inthe art that variations of the preferred embodiments may be used andthat it is intended that the invention may be practiced otherwise thanas specifically described herein. Accordingly, this invention includesall modifications encompassed within the spirit and scope of theinvention as defined by the following claims.

What is claimed is:
 1. A tool holding apparatus for use with amanipulator comprising: a cartridge including a carriage for engaging atool and a guide on which the carriage is movably mounted fortranslation along a path; and a drive unit on which the cartridge isdetachably mounted and which includes a drive mechanism drivablyengageable with the carriage to move the carriage along the path.
 2. Thetool holding apparatus according to claim 31 wherein the path is alinear path.
 3. The tool holding apparatus according to claim 31 whereinthe carriage is adapted for engagement with a biopsy needle.
 4. The toolholding apparatus according to claim 31 wherein the drive mechanismcomprises a lead screw, a nut movable along the lead screw andengageable with the carriage of the carriage of the cartridge, and amotor which can rotate the lead screw to translate the nut along thelead screw.
 5. The tool holding apparatus according to claim 31including a support which supports the drive unit for rotation about anaxis transverse to the path of the carriage.
 6. The tool holdingapparatus according to claim 35 wherein the axis is perpendicular to thepath.
 7. The tool holding apparatus according to claim 35 including adrive mechanism coupled to the drive unit to rotate the drive unit aboutthe axis.
 8. The tool holding apparatus according to claim 37 whereinthe support is adapted for engagement with a manipulator for supportingthe tool holding apparatus.
 9. The tool holding apparatus according toclaim 31 wherein the carriage includes a recess for receiving anenlarged engagement portion of a tool.
 10. The tool holding apparatusaccording to claim 39 wherein the recess is adapted to receive a head ofa needle.
 11. The tool holding apparatus according to claim 39 includinga retainer which fits over the recess to restrain the engagement portionin the recess.
 12. The tool holding apparatus according to claim 31wherein the cartridge includes a guide spaced from the carriage forguiding a shank of a needle as the needle is translated by the carriage.13. The tool holding apparatus according to claim 31 wherein thecartridge includes a dispenser for dispensing a fluid to a patientduring the medical procedure.
 14. The tool holding apparatus accordingto claim 43 wherein the dispenser includes a reservoir for the fluid anda wick extending from the reservoir for transferring fluid from thereservoir to a patient.
 15. The tool holding apparatus according toclaim 43 wherein the dispenser comprises a percutaneous injector. 16.The tool holding apparatus according to claim 31 wherein the cartridgeis adapted to release a tool after positioning.